The cache settings can be found in Tools->Options->Cache. A common complaint by Google Earth users is that the maximum sizes have not been increased for a long time and thus seem somewhat small for todays computers. Currently the maximum disk cache size is 2048 MB and the maximum memory cache size is 1024 MB. If you have sufficient memory and hard disk space then set them to their maximum.
The default location of the cache in Windows is in
%AppData%\LocalLow\Google\GoogleEarth, but it is possible to move it to the location of your choice by modifying the registry setting
HKEY_CURRENT_USER\Software\Google\Google Earth\CachePath for the standard version and
HKEY_CURRENT_USER\Software\Google\Google Earth Pro\CachePath for Google Earth Pro. Since mechanical hard disks are often the slowest part of a modern computer you should experience some performance gains by putting the cache on an SSD if you have one or even a USB 3 memory stick.
We found while using the Google Earth plugin to map historical imagery density that the Google Earth cache filled up about 700mb for each 5 x 5 degree square of the earth. That figure is just approximate, as the area covered by 5 degrees of longitude varies considerably by latitude, and how much the cache gets filled varies depending on what zoom you are at in Google Earth. In addition, we were in ‘historical imagery’ mode, which loads significantly more imagery than the default view. Nevertheless, it demonstrates that caching a whole continent at high resolution is impossible within the current 2 GB limit.
We also discovered that the Google Earth plugin creates its own cache rather than reusing the Google Earth cache. In addition, having multiple instances of the Google Earth plugin open results in multiple caches being created. In our case the total cache folder ended up growing to well over 8GB.